GLK: Check for Manual Override Jumper

vedavis · Post by **vedavis** » Mon Apr 06, 2009 9:39 am

Can the Manual Override jumper across (R5) and (C1) be seen by the Poll Key Press command (0xFE 0x26)?

Raquel · Post by **Raquel** » Mon Apr 06, 2009 2:43 pm

Hi,

Yes, Poll Key Press command should see the key press that shorts R5 and C1. It is by default value 0x55 ('U') on a 5x5 display.

Regards,

Clark · Post by **Clark** » Mon Apr 06, 2009 3:22 pm

Hi Davis,

Just to add to Raquel's post, manual override will act like any other key, so in normal circumstances you will only see the value 0x55 once. After the keypad buffer is polled the value will be gone and you will see 0x00 for subsequent polls.

Turning auto repeat on and the control to typematic style will result in the value being sent repeatedly, but will most likely overrun the buffer. You will also see 0xD5 to signify additional bytes are still in the buffer.

Also of note, no other keys will be read while the manual override jumper is on.

~Troy

vedavis · Post by **vedavis** » Tue Apr 07, 2009 8:11 am

It is true that the unit does transmit a key press of 0x55 when the jumper is placed on the Manual Override pins (R5-C1) while the unit has power. However, it does not have any key press data if the pins are already jumpered when the unit is powered on. The latter scenario was what I was looking to accomplish, so that if the display needed to be re-configured in the field, the Manual Override jumper could be detected and not accidentally remain in place. I tried all permutations of keypad commands to make this happen, but I was unsuccessful. Knowing my application now, is there anything I've missed to accomplish my task? Thanks for your assistance,

Raquel · Post by **Raquel** » Tue Apr 07, 2009 12:46 pm

Due to the nature of how we scan for the rows and columns, if you have the manual override left on, you will not get any keypresses.

Now if you need to find out if the manual override is left on, as Troy suggested, turn the auto repeat on to typematic (cmd 254/126/0) and what you will find is that the display will keep reporting the value 0xD5 (0x55 with bit 7 set to indicate there are more keys to read) if manual override is still on. At this point you probably would want to display something on the screen that says "Please remove Manual Override Jump", so that field operator will be reminded.

vedavis · Post by **vedavis** » Wed Apr 08, 2009 9:52 am

Now if you need to find out if the manual override is left on, as Troy suggested, turn the auto repeat on to typematic...and what you will find is that the display will keep reporting the value 0xD5 (0x55 with bit 7 set to indicate there are more keys to read) if manual override is still on.

This addresses my issue, and it works, and I thank you. Vernon.